Soon, however, another major illness may be confirmed on the list of those triggered or worsened by obesity: Colon cancer, the second leading cancer killer in the United States (after lung cancer).

Gastroenterologists fear that dietary risk factors may account for as many as 90 percent of colorectal cancers and they’ve teamed up with the Campaign to End Obesity (CEO) to spread the news that people with a higher Body Mass Index (BMI) should take extra care to get colorectal monitoring.

Recent studies “suggest that about one-quarter of colorectal cancer cases could be avoided by following a healthy lifestyle,” said Lawrence R. Schiller, president of the American College of Gastroenterology (ACG), in a news statement on the new education program.

While working to improve their diet — by eating less fatty food and more whole grains and fruits and vegetables — Americans who are overweight should take the next step of speaking with their doctor about colon cancer screenings.

“Consumers need to understand the link between a higher Body Mass Index and colorectal cancer, take this risk factor seriously, and talk to their doctor about colorectal cancer tests,” he said in a statement last week.

“Obesity is the precursor to an array of serious diseases, among them colorectal cancer,” said Stephanie Silverman, co-founder of the Campaign to End Obesity. “With two thirds of adults struggling with being overweight or obese, it is essential people understand their long-term health. Fortunately, we have available many useful and practical tools to help people. Screening is one of the most powerful weapons at-hand for preventing colorectal cancer and obesity.”

The education effort aims to help patients understand that medical studies are finding a link between colorectal cancer mortality and metabolic syndrome, a collection of diseases that tend to appear together and increase the risk of having other related illnesses.

Researchers are currently looking at the emerging link between obesity-induced insulin resistance and “hyperinsulinemia” and the development of colorectal cancer.

This all suggests that losing weight, to reduce one’s insulin dependence, could therefore also greatly reduce a person’s risk of colorectal cancer and polyps.

These are the ACG’s screening guidelines:

The ACG recommends that men and women at average risk for colorectal cancer begin screening at age 50. African-Americans should begin colorectal cancer screening at 45. The 2009 ACG evidence-based colorectal cancer screening guidelines distinguish between cancer prevention tests and cancer detection tests. Cancer prevention tests are preferred over detection tests. Colonoscopy every 10 years is the preferred colorectal cancer prevention test.